A serial elastic store (one bit wide) is commonly used as a data buffer that is written into by one clock and read from by another. The elastic store adjusts the period of the data bit from that of the write bit rate to that of the read bit rate and absorbs the differences in the amount of data written into the elastic store and the amount of data read out to take care of short-term instabilities existing in the write and read clocks.
A phase detector may be used to compare the write and read addresses in order to cause data to be placed in a stuff opportunity bit location, as required.
However, a serial elastic store uses a high clock frequency, uses fairly complex circuitry and high power consumption.